The Unitary Plan Wind Tunnel at Ames was designed for aerodynamics research, with air speeds in the transonic and supersonic ranges—up to 3.5 times the speed of sound. The wind tunnel circuits are huge steel conduits that follow rectangular plans.

Diameters vary from 20 ft to 70 ft, and steel thickness ranges from 0.5 in. to 4.5 in. It was made of 15,000 tons of heavy plates of low-carbon steel that had good weld characteristics.

Cylindrical sections of steel plate were joined by automatic welding while they were slowly rotated, but much of the welding was done by hand. Welds were inspected by x-ray and magna flux, and the completed shells were subjected to vacuum tests.

The foundation was challenging, as the underlying strata near San Francisco Bay consisted of alluvial fill and bay mud. Some 1,700 piles were driven to an average depth of 48 ft. Chicago Bridge & Iron Co. was general contractor.

It remains the most heavily used NASA wind tunnel. Every major commercial plane, most military jets, the Mercury, Gemini and Apollo spacecraft, as well as the Space Shuttle were tested there.